CVE-2026-49114Public exploit

Arbitrary file write via symlink-following external-data path

Published Aug 21, 2026 · Updated Aug 21, 2026

Path traversal in ONNX before 1.21.0 allows local users to append data to victim-writable files through crafted external-data paths. save_external_data derives a destination from the model location field, checks it non-atomically, and opens it without exclusive creation or symlink protection. Exploitation requires directory write access and a victim serialization operation, after which a planted link redirects tensor data into files writable by the victim.

CVSS severity7.1
High
EPSS probability0.11%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in ONNX before 1.21.0 allows local users to append data to victim-writable files through crafted external-data paths. save_external_data derives a destination from the model location field, checks it non-atomically, and opens it without exclusive creation or symlink protection. Exploitation requires directory write access and a victim serialization operation, after which a planted link redirects tensor data into files writable by the victim.

The record

CVE
CVE-2026-49114
Published
Aug 21, 2026
Updated
Aug 21, 2026
Vendor
ONNX
Product
ONNX
Classifications
CWE-22, CWE-367, CWE-59
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 21, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <1.21.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

ONNX · ONNXversion=0 <1.21.0

Published CVSS scores

7.1GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
CWE-367Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-59Improper Link Resolution Before File Access ('Link Following')

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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